Sony Dynamic Digital Sound
Sony Dynamic Digital Sound (Japanese: ソニー・ダイナミック・デジタル・サウンド, Hepburn: Sonī Dainamikku Dejitaru Saundo; SDDS) is a cinema sound system developed by Sony, in which compressed digital sound information is recorded on both outer edges of the 35mm film release print. The system supports up to eight independent channels of sound: five front channels, two surround channels and a single sub-bass channel.
Source: Wikipedia — Sony Dynamic Digital Sound (CC BY-SA 4.0)